Improving the Integrity of Lap Joint Flange Connections

2008 ◽  
Author(s):  
Damir Grmek
Keyword(s):  
Lap Joint ◽  
Bolted Connections ◽  
Joint Application ◽  
Number Of Factors ◽  
Bolt Stress ◽  
The Face ◽  
Bolt Holes ◽  
Torque Values ◽  
Spiral Wound

Bolted connections where proper alignment is critical usually require the use of lap joint flanges. The ability of lap joint flanges to swivel around the pipe enables the connection to be installed with no rotational stress applied to the attached piping and equipment. The majority of lap joint flanges on the Enbridge Pipelines system are ANSI 600 and are located at pump nozzles. In these applications, Enbridge Pipelines’ standard specifies the use of spiral wound gaskets with inner rings. Problems with lap joint flanges typically occur at the time of assembly. There are a number of factors that contribute to the challenges of properly seating a gasket in these joints: • Since the raised face is separate from the flange, there is some flex in the face that could unevenly load the gasket; • The flange may not be concentric with the raised face that is welded to the pipe because of clearance between the pipe OD and the flange ID. Using the bolt holes to align the flange does not necessarily ensure that the raised faces are aligned; • Line up pins are not recommended on pump nozzles in order to ensure that no stress is placed on the pump. Consequently, the bottom studs are used to center the gasket and it is possible for the gasket to sit in the stud threads, increasing the misalignment between the gasket windings and the flange raised faces; • Specified torque values for a given flange size may be too high for use in a lap joint application. The perfect bolt alignment in these joints may result in a lower nut factor and subsequently a higher bolt stress for a given torque value. All of these factors can cause damage to the windings on a spiral wound gasket, eventually resulting in a leak. This paper will discuss ways to mitigate these issues.

Novel Formulation of the Tightening and Breakaway Torque Components in Threaded Fasteners

2006 ◽  
Author(s):  
Sayed A. Nassar ◽  
Xianjie Yang
Keyword(s):  
Contact Pressure ◽  
Static Friction ◽  
Bolted Connections ◽  
Friction Coefficients ◽  
Difference Analysis ◽  
Threaded Fasteners ◽  
Thread Profile ◽  
Percent Difference ◽  
Breakaway Torque ◽  
Torque Values

New formulas are developed for the torque-tension relationship, various torque components, and for the break-away torque values in threaded fastener applications. The 3-D aspects of the lead helix and thread profile angles, the kinetic and static friction coefficients are all taken into account. Two scenarios of the contact pressure between threads and under the turning fastener head are considered; namely, uniform distributed and linearly distributed contact pressure scenarios. The effect of thread pitch, lead helix and thread profile angles, friction coefficients, and the fastener geometry is discussed. Results from the new formulas are compared with the approximate torque-tension relationship provided in the literature. A percent difference analysis indicates that the new formulas provide significant improvement that would enhance the reliability and safety of bolted connections, especially in critical applications.

A History of the Target Torque Values From ASME PCC-1 and Future Direction

2017 ◽  
Author(s):  
Clay D. Rodery
Keyword(s):  
Mandatory Requirement ◽  
Bolt Stress ◽  
Original Table ◽  
History Of ◽  
Future Direction ◽  
Torque Values ◽  
Joint Assembly

Since its original issue in 2000, ASME PCC-1 has provided guidance to the user for establishing target torque values for bolted flanged joint assembly. The original tables were developed based on a reference bolt stress of 50 ksi (345 MPa) with guidance provided for making adjustments using other bolt stress values. Despite its attempts to provide clarity, the industry perception has been that the 50 ksi (345 MPa) reference bolt stress is a mandatory requirement, which has never been the intent. This paper reviews the basis of the original Table 1M/Table 1 values provided in PCC-1, and provides a forecast of future improvements utilizing a new concept called a Target Torque Index based on a unit bolt stress, allowing the user to utilize the guidance in Appendix O of PCC-1 to define the appropriate bolt stress for their particular situation.

Cyclic behaviour of bearing-type bolted connections with slot bolt holes

2018 ◽  
Vol 22 (3) ◽  
pp. 792-801
Author(s):  
Guo-qiang Li ◽  
Zhao-xin Hou ◽  
Ying-zhi Sun ◽  
Chao Gong ◽  
Jian Jiang
Keyword(s):  
Energy Dissipation ◽  
Cyclic Load ◽  
High Strength ◽  
Dual Function ◽  
Bolted Connections ◽  
Cyclic Behaviour ◽  
Good Energy ◽  
Bolt Holes ◽  
Energy Dissipation Capacity ◽  
Sliding Force

This article experimentally studies the behaviour of high-strength bolted connections with slot bolt holes under cyclic load to evaluate its seismic performance. A total of six specimens varying in the bolt diameters and pretension are designed and tested. The results show the connections with slot holes have good energy dissipation capacity. It is found that connections with M30 bolts, of which the hysteretic loops are fuller, have better energy dissipation capacity than that of M20 bolts connections. With the increase of number of loading cycles, the sliding force of the connections decreases. On the other hand, the ultimate bearing capacity of the connections does not decrease much both for M30 and M20 bolts. As the experiments proceed, the friction coefficients and the areas of the hysteresis curves decrease in a similar trend because of the smoothing of surfaces. The experimental results indicate the potential application of the connections with slot bolt holes as dual-function parts in structures to simultaneously provide stiffness and energy dissipation capacity.

Explaining the GDR's economic strategy

1986 ◽  
Vol 40 (2) ◽  
pp. 381-420 ◽  
Author(s):  
Thomas A. Baylis
Keyword(s):  
Soviet Union ◽  
Federal Republic ◽  
Political Elite ◽  
Price Shocks ◽  
Economic Strategy ◽  
East European ◽  
The Soviet Union ◽  
Number Of Factors ◽  
The Face

The GDR's fundamental economic strategy since 1971, as reflected in but also modified by its response to the “price shocks” of the 1970s and the ensuing credit squeeze of the early 1980s, has been shaped in important measure by the pressures imposed and the opportunities offered by its complex relationship with the German Federal Republic. The direct and indirect constraints resulting from the GDR's status as junior partner in its alliance with the Soviet Union, the terms of the still tenuous accommodation the regime has worked out with its own citizens, and changes and conflicts within the political elite have also influenced the GDR's choices. The shortterm and long-term measures taken in response to the shocks appear to have been surprisingly successful, even though there is evidence that two of the latter–the return to a policy of economic reform “in small steps” and the utilization of the GDR's “West German connection” to restore its creditworthiness and strengthen its access to Western technology–proceeded only in the face of internal and external controversy. The GDR's apparent success in comparison to its East European neighbors must be attributed to a number of factors, only one of which is its special relationship with the Federal Republic.

scholarly journals Value of Reconstruction Procedures (non-microsurgical) on Facial Defects Postexcision of a Basocellular Carcinomas

2015 ◽  
Vol 21 (2) ◽  
pp. 57-62
Author(s):  
Theodora Dimitropoulou ◽  
I.V Iordache ◽  
T. Poalelungi ◽  
B.M. Caraban ◽  
I. Bordeianu
Keyword(s):  
Primary Outcome ◽  
Defect Size ◽  
Study Group ◽  
Full Thickness ◽  
Reconstructive Procedure ◽  
Number Of Factors ◽  
Facial Defects ◽  
Reconstructive Process ◽  
The Face ◽  
Fascial Plane

Abstract The authors present a retrospective study - 2011-1014 on value of reconstructive nonmicrosurgicals procedures after excisions of facial basocellular carcinomas. The study group included 426 cases of basocellular carcinomas of the face (primary diagnosed or recurrent) that required reconstructive procedure after excision in oncology margin (according to the criteria of the clinic). The choice is eclectically considering reconstructive process (evaluating) a number of factors: patient age, location of carcinoma, post excisional defect size and pathological status (recurrence, radiation) and the frequency of the primary outcome was using plastic reconstruction of full-thickness free skin. All cases included in the study received a performant dermatoscopic exam and excisions were performed at 5-10 mm from the edges of the apparent surface and in deepness in fascial plane.

Relaxation of the Bolted Flange Connection

2020 ◽  
Author(s):  
Robert Taylor
Keyword(s):  
Internal Pressure ◽  
Temperature Cycling ◽  
Bolted Connection ◽  
Relaxation Properties ◽  
Flange Connection ◽  
Bolt Stress ◽  
Bolted Flange ◽  
Spiral Wound

Abstract This study researches the total relaxation of a bolted flange connection, taking into account, the relaxation of various bolt grades in conjunction with different semi-metallic gaskets. The test temperatures are: 300 °F (149 °C), 500 °F (260 °C), 650 °F (343 °C) and 800 °F (427 °C), where each temperature setting will cycle three times to obtain the relaxation value for each cycle. The three types of bolt materials for evaluation include ASTM A193 B7, ASTM A193 B16 and ASTM B8M CL2 along with gaskets styles of spiral wound gasket with inner ring, spiral wound gasket with NO inner ring and the kammprofile gasket (grooved metal gasket with covering layers), all in accordance to ASME B16.20 – 2017. The above variations and conditions will be tested at two different initial bolt stresses of 35,000 psi (241 MPa) and 65,000 psi (448 MPa) with a constant internal pressure of 150 psi (10.3 Bar). The results will show relaxation values for the different bolt and gasket types versus the various temperature cycling conditions indicated above. Focusing on: does a certain gasket style offer lower relaxation properties through less creep and/or higher recovery? Does a certain bolt grade offer better stress retention? Is there variation in initial bolt stress for the different style of gasket? How does the initial bolt stress affect the relaxation properties of the bolted connection?

The Regulation of the Pharmaceutical Industry

2010 ◽  
pp. 547-571
Author(s):  
Adrian Towse ◽  
Patricia M. Danzon
Keyword(s):  
Pharmaceutical Industry ◽  
Natural Monopoly ◽  
Developed Country ◽  
Advantages And Disadvantages ◽  
Private Sector Investment ◽  
Number Of Factors ◽  
Form Of Government ◽  
The Face ◽  
Less Developed Country ◽  
Push And Pull

This article focuses on the pharmaceutical industry. The pharmaceutical industry (including biological therapies and vaccines) is heavily regulated and yet has no intrinsic natural monopoly characteristics. Indeed it is highly competitive from research through to selling. Market power is temporary and derived from public policy in the form of government-granted patents on individual products. The regulatory issues in pharmaceuticals therefore arise from a number of factors that characterise this field. This article looks at the special challenges of regulating in the face of such factors as poor observability of efficacy, high dangers of moral hazard, and the potential exclusion from desirable services of those who lack wealth. In response to the need for private sector investment in drugs and vaccines to treat Less Developed Country-only diseases, the advantages and disadvantages of ‘push’ and ‘pull’ subsidy proposals are also considered in this article.

Public Policy and Shopping Effectiveness: The Case of Item-Price Removal

1983 ◽  
Vol 2 (1) ◽  
pp. 70-81
Author(s):  
Michael K. Mills ◽  
Brian F. Harris
Keyword(s):  
Public Policy ◽  
Policy Issue ◽  
Policy Decision ◽  
Grocery Stores ◽  
Price Information ◽  
Public Policy Issue ◽  
Number Of Factors ◽  
The Face ◽  
Item Price

The removal of item prices in scanner equipped grocery stores is an important public policy issue, as it relates to the ability of consumers to engage in effective shopping in the face of decreased price information. This study analyzed the possible role of public policy in this area by investigating the likely impact of item-price removal in scanner-equipped grocery stores. A number of factors that bear on the role of public policy were analyzed, including consumers’ use of price information, their general attitudes toward retailers, and their experience with and attitudes toward scanner technology. Particular emphasis was paid to the likely impact of item-price removal on the shopping effectiveness of the disadvantaged elderly and minorities. The findings of the study point to a number of possible directions for public policy decision making in this area.

scholarly journals Bolts Gauge Effect on the Face Bending Behaviour of Concrete-Filled Hollow Section for Hollo-Bolted Connections

2015 ◽  
Vol 773-774 ◽  
pp. 105-109 ◽  
Author(s):  
Ahmed Elamin ◽  
Walid Tizani ◽  
Mohammed Mahmood
Keyword(s):  
Width Ratio ◽  
Bolted Connections ◽  
Initial Stiffness ◽  
Structural Behaviour ◽  
Hollow Section ◽  
Typical Experiment ◽  
The Face ◽  
Exact Size ◽  
Yield Force ◽  
Bending Behaviour

This paper investigates the effect of bolt gauge on the face bending behaviour of concrete-filled Square Hollow Sections (SHS) in Hollo-Bolted connections. A set of full-scale experiments were undertaken to examine the effects of varying the bolt gauge on the SHS face bending behaviour while controlling all other parameters. Typical experiment involved one row of two bolts pulled out of concrete-filled SHS. A special dummy bolts were manufactured to the exact size and geometry of open Hollo-Bolts, and were used in the experiments to remove the influence of any deformation associated with the real Hollo-Bolts, and isolate the face bending behaviour. Non-contact video-based equipment was used to record the SHS face deformation. This deformation is recorded as force-displacement relationship which is commonly used to represent the structural behaviour of similar components, and typically defined by initial stiffness, yield force and post yield stiffness. Across the range considered in this investigation, it was found that varying the bolt gauge to SHS width ratio have a significant effect on the concrete-filled SHS face in bending component. Both the initial stiffness and the yield force of the component were found to increase with the increase of the bolt gauge. The Post-Yield stiffness was not affected by the change in bolt gauge.

The Polish Party in Crisis, 1980–1982

Slavic Review ◽  
1984 ◽  
Vol 43 (1) ◽  
pp. 30-45 ◽  
Author(s):  
David S. Mason
Keyword(s):  
Communist Party ◽  
Martial Law ◽  
Party Organizations ◽  
Leading Role ◽  
Number Of Factors ◽  
The Face ◽  
Open Discussion ◽  
The Military ◽  
Local Party

Over the last three years, the Polish United Workers’ Party has suffered a major crisis, the most substantial crisis of any Communist party in any Communist party state. The disintegration of the party was at least partly responsible for both the development of Solidarity in the summer of 1980 and the imposition of martial law in December 1981. The lack of trust in the party and its authoritarian and unrepresentative character led the workers to demand an institution more responsive to their own needs. But the growth of Solidarity during 1981 and the continuing disintegration and fragmentation of the party led the military to preempt the leading role of the party in 1982.The collapse of the party in 1980 and 1981 was due to a number of factors. The party leadership had to bear the burden of the economic failures of the late 1970s and the consequent decline in the standard of living. The party itself had grown rapidly in size during that period, even though the influence of ordinary party members and local party organizations declined in the face of increasing tendencies toward centralization in the second half of the decade. This development led to problems of morale even within the party and to the growth of horizontal barriers between the membership and its leaders. The population at large was increasingly annoyed and disgusted with the failure of the party to improve the economic situation and to allow a more honest and open discussion of Poland's problems. The dissatisfaction was compounded by the widespread perception that the elite was increasingly looking after its own interests only and that benefits and privileges were accruing only to those in power.

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